Must be an excellent simple design. Two easy tactics to reach this, each can also be mixed if you wish to have as smartly. 1) have the fins slider tapered so the because it slides down into the grooves to carry it, it’s going to turn into an interference are compatible and keep beautiful tightly in position. Be sure the taper goes in opposition to the rockets course; ie rocket goes up, you wish to have the taper the place you hobby the fin from nostril to tail course. Use a rubber mallet or one thing to get the fin to the designated place, and use the mallet additionally to knock it lose to disassemble and service. 2) have the groove have a backing at the rear that forestalls the fin. Are compatible must be an interference are compatible to stop the load of the rocket from knocking them lose whilst it rests at the release pad. In fact combining each would give the most productive effects.